Method for forming carbon-containing silicon/metal oxide or nitride film by ald using silicon precursor and hydrocarbon precursor

ABSTRACT

An oxide or nitride film containing carbon and at least one of silicon and metal is formed by ALD conducting one or more process cycles, each process cycle including: feeding a first precursor in a pulse to adsorb the first precursor on a substrate; feeding a second precursor in a pulse to adsorb the second precursor on the substrate; and forming a monolayer constituting an oxide or nitride film containing carbon and at least one of silicon and metal on the substrate by undergoing ligand substitution reaction between first and second functional groups included in the first and second precursors adsorbed on the substrate. The ligand may be a halogen group, —NR 2 , or —OR.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/341,500, entitled “Method for Forming Carbon-ContainingSilicon/Metal oxide or Nitride Film by ALD Using Silicon Precursor andHydrocarbon Precursor,” and filed on May 25, 2016, which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention generally relates to a method for forming acarbon-containing silicon/metal oxide or nitride film by atomic layerdeposition (ALD) using a silicon/metal precursor and a hydrocarbonprecursor.

Description of the Related Art

As a method for forming an amorphous film containing carbon, such as aSiC film, SiCN film, or the like, chemical vapor deposition (CVD) hasbeen used for long time. However, when a plasma is used (i.e.,plasma-enhanced CVD), surface reaction significantly occurs, lowering astep coverage. On the other hand, when heat is used (i.e., thermal CVD),extremely high process temperature is required, lowering practicability.

The present inventors have evaluated atomic layer deposition (ALD) forforming a carbon-containing amorphous film since ALD is known for goodstep coverage. However, in some cases, carbon contained in a precursorwas not effectively adsorbed on a surface, especially on a sidewall of atrench pattern of a substrate, and thus, a film deposited on thesidewall became thin, lowering step coverage. The above problem becamesignificant particularly when the size of the pattern was small. Forexample, when a carbon-containing amorphous film was deposited in atrench pattern having an opening of 70 nm and an aspect ratio of 2, thestep coverage was approximately 90%, whereas when a carbon-containingamorphous film was deposited in a trench pattern having an opening of 30nm and an aspect ratio of 3.5, the step coverage was drastically loweredto approximately 60%.

Thus, in a process which requires incorporation of SiC into a film, theadsorption of carbon tends to be low on a sidewall, and the stepcoverage on the sidewall tends to suffer. This problem occurredsimilarly for a film such as those constituted by SiCO, SiCN, or thelike, although the step coverage of these films was better than that ofa film constituted by SiC since these films contained nitrogen or oxygenas compared with the pure SiC film. That is, not only a SiC film, butalso a SiCO film, SiCN film, or the like, had insufficient step coveragewhen being deposited in a small size trench pattern. The use of a plasmamay contribute to the above problem since less plasma tends to reach asidewall especially when a trench pattern is small. Based on the aboveexperiment, the present inventors have worked on a new method toeliminate elements which interfere with adsorption of carbon on asidewall.

Any discussion of problems and solutions in relation to the related arthas been included in this disclosure solely for the purposes ofproviding a context for the present invention, and should not be takenas an admission that any or all of the discussion was known at the timethe invention was made.

SUMMARY OF THE INVENTION

In some embodiments, by using two different precursors having differentligands which easily cause ligand substitution reaction, at least one ofthe above-discussed problems can be resolved. In some embodiments, aprecursor is divided into two precursors wherein a first precursorprovides at least silicon or metal, and a second precursor providescarbon, and both the first and second precursors contain ligands whichcan effectively cause ligand substitution reaction. In some embodiments,a combination of ligands which can effectively cause ligand substitutionreaction is a combination of a halogen group and —NR₂, a halogen groupand —OR, a halogen group and halogen group, or —NR₂ and —OR. The secondprecursor contains important components which determine filmcompositions. For example, the second precursor for forming an oxidefilm such as SiCO, SiOCN, or the like may require inclusion of ahydroxyl group as a ligand to form oxide, whereas the second precursorfor forming a nitride film such as SiCN or the like may requireinclusion of a C—N bond as a ligand to form nitride. The same approachcan be taken for a metal oxide, metal nitride, or the like, where ametal, in place of silicon, constitutes a basic structure or primaryskeleton of the first precursor. The ligand substitution reaction occursat a certain temperature, and thus, thermal ALD can be employed fordepositing a film; however, a plasma may be used in a situation whereadsorption of a precursor needs to be improved, as in plasma-enhancedALD.

For purposes of summarizing aspects of the invention and the advantagesachieved over the related art, certain objects and advantages of theinvention are described in this disclosure. Of course, it is to beunderstood that not necessarily all such objects or advantages may beachieved in accordance with any particular embodiment of the invention.Thus, for example, those skilled in the art will recognize that theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

Further aspects, features and advantages of this invention will becomeapparent from the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will now be described withreference to the drawings of preferred embodiments which are intended toillustrate and not to limit the invention. The drawings are greatlysimplified for illustrative purposes and are not necessarily to scale.

FIG. 1A is a schematic representation of a PEALD (plasma-enhanced atomiclayer deposition) apparatus for depositing a protective film usable inan embodiment of the present invention.

FIG. 1B illustrates a schematic representation of a precursor supplysystem using a flow-pass system (FPS) usable in an embodiment of thepresent invention, wherein a precursor will be fed to a reactor in (a)and no precursor will be fed to the reactor in (b).

FIG. 2 illustrates a precursor supply system using an auto-pressureregulator (APR) according to an embodiment of the present invention,wherein a precursor will be fed to a reactor in (a) and no precursorwill be fed to the reactor in (b).

FIG. 3 illustrates a precursor supply system using a bottle-out controlsystem (BTO) according to an embodiment of the present invention,wherein a precursor will be fed to a reactor in (a) and no precursorwill be fed to the reactor in (b).

FIG. 4 illustrates a precursor supply system using an APR with a BTOaccording to an embodiment of the present invention, wherein a precursorwill be fed to a reactor in (a) and no precursor will be fed to thereactor in (b).

FIG. 5 shows a schematic process sequence of PEALD in one cycleaccording to a comparative example wherein a cell in gray represents anON state whereas a cell in white represents an OFF state, and the widthof each column does not represent duration of each process.

FIG. 6 shows a schematic process sequence of PEALD in one cycleaccording to an embodiment of the present invention wherein a cell ingray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess.

FIG. 7 shows a schematic process sequence of PEALD in one cycleaccording to another embodiment of the present invention wherein a cellin gray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess.

FIG. 8 shows a schematic process sequence of thermal ALD in one cycleaccording to an embodiment of the present invention wherein a cell ingray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess.

FIG. 9 shows a schematic process sequence of thermal ALD in one cycleaccording to another embodiment of the present invention wherein a cellin gray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess.

FIG. 10 shows a schematic process sequence of PEALD in one cycle,followed by the schematic process sequence of PEALD illustrated in FIG.6 or 7 according to an embodiment of the present invention wherein acell in gray represents an ON state whereas a cell in white representsan OFF state, and the width of each column does not represent durationof each process.

FIG. 11 shows a schematic process sequence according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

In this disclosure, “gas” may include vaporized solid and/or liquid andmay be constituted by a single gas or a mixture of gases. In thisdisclosure, a process gas introduced to a reaction chamber through ashowerhead may be comprised of, consist essentially of, or consist of aprecursor gas and an additive gas. The precursor gas and the additivegas are typically introduced as a mixed gas or separately to a reactionspace. The precursor gas can be introduced with a carrier gas such as anoble gas. The additive gas may be comprised of, consist essentially of,or consist of a reactant gas and a dilution gas such as a noble gas. Thereactant gas and the dilution gas may be introduced as a mixed gas orseparately to the reaction space. A precursor may be comprised of two ormore precursors, and a reactant gas may be comprised of two or morereactant gases. The precursor is a gas chemisorbed on a substrate andtypically containing a metalloid or metal element which constitutes amain structure of a matrix of a dielectric film, and the reactant gasfor deposition is a gas reacting with the precursor chemisorbed on asubstrate when the gas is excited to fix an atomic layer or monolayer onthe substrate. “Chemisorption” refers to chemical saturation adsorption.A gas other than the process gas, i.e., a gas introduced without passingthrough the showerhead, may be used for, e.g., sealing the reactionspace, which includes a seal gas such as a noble gas. In someembodiments, “film” refers to a layer continuously extending in adirection perpendicular to a thickness direction substantially withoutpinholes to cover an entire target or concerned surface, or simply alayer covering a target or concerned surface. In some embodiments,“layer” refers to a structure having a certain thickness formed on asurface or a synonym of film or a non-film structure. A film or layermay be constituted by a discrete single film or layer having certaincharacteristics or multiple films or layers, and a boundary betweenadjacent films or layers may or may not be clear and may be establishedbased on physical, chemical, and/or any other characteristics, formationprocesses or sequence, and/or functions or purposes of the adjacentfilms or layers.

Further, in this disclosure, the article “a” or “an” refers to a speciesor a genus including multiple species unless specified otherwise. Theterms “constituted by” and “having” refer independently to “typically orbroadly comprising”, “comprising”, “consisting essentially of”, or“consisting of” in some embodiments. Also, in this disclosure, anydefined meanings do not necessarily exclude ordinary and customarymeanings in some embodiments.

Additionally, in this disclosure, any two numbers of a variable canconstitute a workable range of the variable as the workable range can bedetermined based on routine work, and any ranges indicated may includeor exclude the endpoints. Additionally, any values of variablesindicated (regardless of whether they are indicated with “about” or not)may refer to precise values or approximate values and includeequivalents, and may refer to average, median, representative, majority,etc. in some embodiments.

In the present disclosure where conditions and/or structures are notspecified, the skilled artisan in the art can readily provide suchconditions and/or structures, in view of the present disclosure, as amatter of routine experimentation. In all of the disclosed embodiments,any element used in an embodiment can be replaced with any elementsequivalent thereto, including those explicitly, necessarily, orinherently disclosed herein, for the intended purposes. Further, thepresent invention can equally be applied to apparatuses and methods.

The embodiments will be explained with respect to preferred embodiments.However, the present invention is not limited to the preferredembodiments.

An embodiment of the present invention provides a method for forming anoxide or nitride film containing carbon and at least one of silicon andmetal in a trench on a substrate placed in a reaction space by atomiclayer deposition (ALD) conducting one or more process cycles, eachprocess cycle comprising:

-   -   (i) feeding a first precursor in a pulse to the reaction space        to adsorb the first precursor on the substrate, said first        precursor containing at least one of silicon and metal, and a        first functional group selected from the group consisting of a        halogen group, —NR₂, and —OR, wherein each R independently        represents hydrogen or hydrocarbon group;    -   (ii) feeding a second precursor in a pulse to the reaction space        to adsorb the second precursor on the substrate, said second        precursor containing neither silicon nor metal, and a second        functional group selected from the group consisting of a halogen        group, —NR₂, and —OR, wherein each R independently represents        hydrogen or hydrocarbon group, wherein the first and second        functional groups are a combination of a halogen group and —NR₂,        a halogen group and —OR, a halogen group and halogen group, or        —NR₂ and —OR; and    -   (iii) forming a monolayer constituting an oxide or nitride film        containing carbon and at least one of silicon and metal on the        substrate by undergoing a substitution reaction between the        first and second functional groups of the first and second        precursors adsorbed on the substrate.

Accordingly, a carbon-containing film can successfully be formed withgood conformality (e.g., more than 90%) even on sidewalls of a trenchhaving an aspect ratio of more than 2, for example, by using the firstand second precursors in combination, wherein the first precursorcontains silicon (or metal) and at least one first ligand, and thesecond precursor contains no silicon (nor metal) and at least one secondligand, where the first ligand and the second ligand can undergo ligandsubstitution reaction.

Ligand substitution reaction can occur between —NR₂⇄—OR;hydrogen⇄hydrogen; hydrogen⇄—NR₂; and hydrogen⇄—OR, regardless of themain skeleton of the first and second precursors. For example, thefollowing combinations of precursors can effectively undergo ligandsubstitution reaction:

TABLE 1 Combination of precursors Reactant Film Diiodosilane +Iodomethane H₂ plasma SiC Diiodosilane + Diiodomethane H₂ plasma SiCDisilabutane (H₃SiCH₂CH₂H₃) + H₂ plasma SiC DiiodomethaneDivinylmethylsilane + Diiodomethane H₂ plasma SiC Bisdiethyaminosilane +Ethyleneglycol O₂ plasma SiCO Triethylsilanol + glycerol H₂ gas SiCOTris(t-pentoxi)silanol H₂ gas SiCO ((CH₃)₃CO)₃SiOH) + EthyleneglycolDiiodosilane + Diethylamine H₂ gas/plasma; SiCN NH₃ gas/plasmaBisdimethylaminosilane + Diiodomethane H₂ gas/plasma; SiCN NH₃gas/plasma

The functional groups contained in the first and second precursors maybe referred to as “ligands” which undergo ligand substitution reaction.Either one of steps (i) and (ii) can start first; that is, the order ofsteps (i) and (ii) can be reversed.

The first precursor contains at least one of silicon and metal. Themetal includes, but is not limited to, Zr, Ti, etc., wherein the firstprecursor includes, but is not limited to, trisdiethylamino titanium,trisdimethylaminocyclopentadienyl zirconium, etc., forming a filmconstituted by TiOC, ZrOC, etc.

In some embodiments, the first precursor is one or more compoundsselected from the group consisting of:

wherein each X is independently H, C_(x)H_(y), NH₂, NH(C_(x)H_(y)),N(C_(x)H_(y))₂, O(C_(x)H_(y)), or OH, each Y is independently F, Cl, Br,I, NH₂, NH(C_(x)H_(y)), or N(C_(x)H_(y))₂, and each Z is independentlyC_(x)H_(y) or N_(x)H_(y), wherein x and y are integers.

In some embodiments, the second precursor is one or more compoundsselected from the group consisting of:

wherein each X is independently C_(x)O_(y), O(C_(x)H_(y)), NH₂,NH(C_(x)H_(y)), N(C_(x)H_(y))₂, or OH, each Y is independentlyC_(x)H_(y) or N_(x)H_(y), each A is independently H or C_(x)H_(y), andeach B is OH, C_(x)H_(y), O(C_(x)H_(y)), NH₂, NH(C_(x)H_(y)),N(C_(x)H_(y))₂, F, Cl, Br, or I, wherein x and y are integers.

In some embodiments, the first and second functional groups are analkylamino group and a hydroxyl group, respectively, or a halogen groupand a halogen group, respectively.

In some embodiments, a noble gas is continuously fed to the reactionspace throughout the process cycle. In some embodiments, each processcycle further comprises a purging step between steps (i) and (ii), andbetween steps (ii) and (i) if the process cycle is repeated.

In some embodiments, the precursor is fed in a pulse to the reactionspace using a flow-pass system (FPS), auto-pressure regulator (APR), ora bottle-out control system (BTO).

In some embodiments, the oxide or nitride film is a film constituted bySiC, SiCO, SiCN, or SiCON.

In some embodiments, the ALD is thermal ALD, and the substitutionreaction is thermally performed.

In some embodiments, the ALD is plasma-enhanced ALD, and thesubstitution reaction is performed using a plasma. In some embodiments,a reactant gas is fed continuously to the reaction space throughout eachprocess cycle. The reactant gas may be one or more gases selected fromthe group consisting of O₂, H₂, NH₃, and N₂.

In some embodiments, a sidewall coverage and a bottom coverage are 90%or higher, wherein the sidewall coverage is defined as a ratio ofthickness of film on a sidewall of the trench to thickness of film on ablanket surface (a top surface of the substrate) at the trench, and thebottom coverage is defined as a ratio of thickness of film on a bottomof the trench to thickness of film on the blanket surface at the trench.

In some embodiments, in step (iii), the monolayer is constituted by SiCor SiCO, and each process cycle further comprises, after step (iii):

-   -   (iv) switching the reactant gas to another reactant gas and        feeding the another reactant continuously to the reaction space,    -   (v) feeding a third precursor in a pulse to the reaction space        to adsorb the third precursor on the substrate, said third        precursor containing at least one of silicon and metal and being        reactive with excited species of the another reactant; and    -   (vi) applying RF power to the reaction space to excite the        another reactant to react with the third precursor adsorbed on        the monolayer or monolayers obtained in step (iii) to form        thereon a monolayer or monolayers constituting a nitride film        containing at least one of silicon and metal.

By introducing Si—N bonds to a SiC/SiCO film, heat resistance and/orchemical resistance of the film can significantly be improved.

Some embodiments will be explained with respect to the drawings.However, the present invention is not limited to the embodiments.

FIG. 11 shows a schematic process sequence according to an embodiment ofthe present invention. In this sequence, an oxide or nitride filmcontaining carbon and at least one of silicon and metal in a trench on asubstrate placed in a reaction space is formed by atomic layerdeposition (ALD) conducting one or more process cycles, each processcycle comprising: (i) feeding a first precursor in a pulse to thereaction space to adsorb the first precursor on the substrate, saidfirst precursor containing at least one of silicon and metal, and afirst functional group (step S11); (ii) feeding a second precursor in apulse to the reaction space to adsorb the second precursor on thesubstrate, said second precursor containing neither silicon nor metal,and a second functional group (step S12); and (iii) forming a monolayerconstituting an oxide or nitride film containing carbon and at least oneof silicon and metal on the substrate by undergoing a substitutionreaction between the first and second functional groups of the first andsecond precursors adsorbed on the substrate (step S13), wherein steps(i) to (iii) (steps S11, S12, and S13) are repeated until a desiredthickness (e.g., 2 to 100 nm, typically 5 nm to 20 nm, depending on theintended use, etc.) of the film is obtained.

FIGS. 1 to 4 are schematic views of a plasma-enhanced ALD reactor andflow control systems, desirably in conjunction with controls programmedto conduct the sequences described below, which can be used in anembodiment of the present invention. A skilled artisan will appreciatethat the apparatus includes one or more controller(s) (not shown)programmed or otherwise configured to cause the deposition and reactorcleaning processes described elsewhere herein to be conducted. Thecontroller(s) are communicated with the various power sources, heatingsystems, pumps, robotics, and gas flow controllers or valves of thereactor, as will be appreciated by the skilled artisan.

In some embodiments, the process sequence may be set as illustrated inFIG. 6. FIG. 6 shows a schematic process sequence of PEALD in one cycleaccording to an embodiment of the present invention wherein a cell ingray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess. In this embodiment, one cycle of PEALD comprises “1^(st) Feed”where a first precursor gas (e.g., a Si-containing precursor gas) is fedto a reaction space via a carrier gas which carries the first precursorwithout feeding a second precursor and without applying RF power to thereaction space, and also, a dilution gas and a reactant gas are fed tothe reaction space, thereby chemisorbing the first precursor gas onto asurface of a substrate via self-limiting adsorption; “Purge” where nofirst precursor nor second precursor is fed to the reaction space, whilethe carrier gas, the dilution gas, and reactant gas are continuously fedto the reaction space, without applying RF power, thereby removingnon-chemisorbed precursor gas and excess gas from the surface of thesubstrate; “2^(nd) Feed” where a second precursor gas (e.g., ahydrocarbon-containing precursor gas) is fed to the reaction space via acarrier gas which carries the second precursor without feeding the firstprecursor and without applying RF power to the reaction space, and also,the dilution gas and the reactant gas are continuously fed to thereaction space, thereby chemisorbing the second precursor gas onto thefirst precursor-adsorbed surface of the substrate via self-limitingadsorption; “Purge” where no first precursor nor second precursor is fedto the reaction space, while the carrier gas, the dilution gas, andreactant gas are continuously fed to the reaction space, withoutapplying RF power, thereby removing non-chemisorbed precursor gas andexcess gas from the surface of the substrate; “RF” where RF power isapplied to the reaction space while the carrier gas, the dilution gas,and reactant gas are continuously fed to the reaction space, withoutfeeding the first and second precursors, thereby forming a monolayerthrough plasma surface reaction with the reactant gas in an excitedstate, wherein the ligand of the first precursor gas and the ligand ofthe second precursor gas undergo ligand substitution reaction to form amonolayer; and “Purge” where the carrier gas, the dilution gas, andreactant gas are continuously fed to the reaction space, without feedingthe first and second precursors and without applying RF power to thereaction space, thereby removing by-products and excess gas from thesurface of the substrate. The carrier gas can be constituted by thereactant gas. Due to the continuous flow of the carrier gas enteringinto the reaction space as a constant stream into which the first orsecond precursor is injected intermittently or in pulses, purging can beconducted efficiently to remove excess gas and by-products quickly fromthe surface of the layer, thereby efficiently continuing multiple ALDcycles.

The sequence illustrated in FIG. 6 can be performed under the conditionsshown in Table 2 below.

TABLE 2 (numbers are approximate) Conditions for PEALD Cycle (Sequence#2) Substrate temperature 50 to 600° C. (preferably 100 to 400° C.)Pressure 50 to 4000 Pa (preferably 133 to 1000 Pa) 1^(st) precursorpulse 0.1 to 2 sec (preferably 0.3 to 1 sec) 1^(st) precursor purge 0.1to 10 sec (preferably 0.5 to 1 sec) 2^(nd) precursor pulse 0.1 to 2 sec(preferably 0.3 to 1 sec) 2^(nd) precursor purge 0.1 to 10 sec(preferably 0.5 to 1 sec) Flow rate of reactant 10 to 2000 sccm(preferably 50 to 500 sccm) (continuous) for SiC; 10 to 2000 sccm(preferably 50 to 500 sccm) for SiCO; 10 to 2000 sccm (preferably 50 to500 sccm) for SiCN Carrier gas 1000 to 5000 sccm (preferably 2000 to4000 sccm) Dilution gas 0 to 5000 sccm (preferably 0 to 2000 sccm) RFpower (13.56 MHz) 30 to 1000 W (preferably 50 to 200 W) for a 300-mmwafer RF power pulse 0.1 to 10 sec (preferably 0.2 to 5 sec) Purge 0.1to 5 sec (preferably 0.1 to 1 sec) Growth rate per cycle 0.01 to 0.1nm/cycle (on a top surface)

In this disclosure, the wattage of RF power for a 300-mm wafer can beexpressed using units W/cm² which can be applied to a different size ofsubstrate such as a 200-mm substrate and a 450-mm substrate; likewise,“W” can be converted to “W/cm²” in this disclosure. Further, in place ofdirect plasma, remote plasma can be used to form active species ofreactant in the reaction space.

In the above process sequence, the precursor is supplied in a pulseusing a carrier gas which is continuously supplied. This can beaccomplished using a flow-pass system (FPS) wherein a carrier gas lineis provided with a detour line having a precursor reservoir (bottle),and the main line and the detour line are switched, wherein when only acarrier gas is intended to be fed to a reaction chamber, the detour lineis closed, whereas when both the carrier gas and a precursor gas areintended to be fed to the reaction chamber, the main line is closed andthe carrier gas flows through the detour line and flows out from thebottle together with the precursor gas. In this way, the carrier gas cancontinuously flow into the reaction chamber, and can carry the precursorgas in pulses by switching the main line and the detour line. FIG. 1Billustrates a precursor supply system using a flow-pass system (FPS)according to an embodiment of the present invention (black valvesindicate that the valves are closed). As shown in (a) in FIG. 1B, whenfeeding a precursor to a reaction chamber (not shown), first, a carriergas such as Ar (or He) flows through a gas line with valves b and c, andthen enters a bottle (reservoir) 20. The carrier gas flows out from thebottle 20 while carrying a precursor gas in an amount corresponding to avapor pressure inside the bottle 20, and flows through a gas line withvalves f and e, and is then fed to the reaction chamber together withthe precursor. In the above, valves a and d are closed. When feedingonly the carrier gas (noble gas) to the reaction chamber, as shown in(b) in FIG. 1B, the carrier gas flows through the gas line with thevalve a while bypassing the bottle 20. In the above, valves b, c, d, e,and f are closed.

The precursor may be provided with the aid of a carrier gas. Since ALDis a self-limiting adsorption reaction process, the number of depositedprecursor molecules is determined by the number of reactive surfacesites and is independent of precursor exposure after saturation, and asupply of the precursor is such that the reactive surface sites aresaturated thereby per cycle. A plasma for deposition may be generated insitu, for example, in an ammonia gas that flows continuously throughoutthe deposition cycle. In other embodiments the plasma may be generatedremotely and provided to the reaction chamber.

As mentioned above, each pulse or phase of each deposition cycle ispreferably self-limiting. An excess of reactants is supplied in eachphase to saturate the susceptible structure surfaces. Surface saturationensures reactant occupation of all available reactive sites (subject,for example, to physical size or “steric hindrance” restraints) and thusensures excellent step coverage. In some embodiments the pulse time ofone or more of the reactants can be reduced such that completesaturation is not achieved and less than a monolayer is adsorbed on thesubstrate surface.

The process cycle can be performed using any suitable apparatusincluding an apparatus illustrated in FIG. 1A, for example. FIG. 1A is aschematic view of a PEALD apparatus, desirably in conjunction withcontrols programmed to conduct the sequences described below, usable insome embodiments of the present invention. In this figure, by providinga pair of electrically conductive flat-plate electrodes 4, 2 in paralleland facing each other in the interior 11 (reaction zone) of a reactionchamber 3, applying HRF power (13.56 MHz or 27 MHz) 20 to one side, andelectrically grounding the other side 12, a plasma is excited betweenthe electrodes. A temperature regulator is provided in a lower stage 2(the lower electrode), and a temperature of a substrate 1 placed thereonis kept constant at a given temperature. The upper electrode 4 serves asa shower plate as well, and reactant gas (and noble gas) and precursorgas are introduced into the reaction chamber 3 through a gas line 21 anda gas line 22, respectively, and through the shower plate 4.Additionally, in the reaction chamber 3, a circular duct 13 with anexhaust line 7 is provided, through which gas in the interior 11 of thereaction chamber 3 is exhausted. Additionally, a dilution gas isintroduced into the reaction chamber 3 through a gas line 23. Further, atransfer chamber 5 disposed below the reaction chamber 3 is providedwith a seal gas line 24 to introduce seal gas into the interior 11 ofthe reaction chamber 3 via the interior 16 (transfer zone) of thetransfer chamber 5 wherein a separation plate 14 for separating thereaction zone and the transfer zone is provided (a gate valve throughwhich a wafer is transferred into or from the transfer chamber 5 isomitted from this figure). The transfer chamber is also provided with anexhaust line 6. In some embodiments, the deposition of multi-elementfilm and surface treatment are performed in the same reaction space, sothat all the steps can continuously be conducted without exposing thesubstrate to air or other oxygen-containing atmosphere. In someembodiments, a remote plasma unit can be used for exciting a gas.

In some embodiments, in the apparatus depicted in FIG. 1A, the system ofswitching flow of an inactive gas and flow of a precursor gasillustrated in FIG. 1B (described earlier) can be used to introduce theprecursor gas in pulses without substantially fluctuating pressure ofthe reaction chamber.

The precursor can be fed in a pulse to the reaction space not only usinga flow-pass system (FPS), but also auto-pressure regulator (APR), abottle-out control system (BTO), or mass flow controller (MFC). FIG. 2illustrates a precursor supply system using an auto-pressure regulator(APR) according to an embodiment of the present invention. As shown in(a) in FIG. 2, when feeding a precursor to a reaction chamber (notshown), first, a carrier gas flows through a gas line with valves b andc, and then enters a bottle 20. The carrier gas flows out from thebottle 20 while carrying a precursor gas in an amount corresponding to avapor pressure inside the bottle 20, and flows through a gas line withvalves f and e, and is then fed to the reaction chamber together withthe precursor through an auto-pressure regulator (APR) 30 and a valve gprovided in a gas line upstream of the reaction chamber. In the above,valves a and d are closed. Valve g is an on-off valve, and whenpreventing the precursor from entering into the reaction chamber, asshown in (b) in FIG. 2, valve g is closed so that neither the precursornor the carrier gas is fed to the reaction chamber.

FIG. 3 illustrates a precursor supply system using a bottle-out controlsystem (BTO) according to an embodiment of the present invention. Asshown in (a) in FIG. 3, when a carrier gas flows through a gas line witha valve a to a reaction chamber (not shown) without passing through abottle 20, a precursor gas enters into a stream of the carrier gaspassing through the gas line where a gas line from the bottle 20 meetsthe gas line through which the carrier gas flows, and the carrier gascarries the precursor therefrom and is then fed to the reaction chambertogether with the precursor. In the above, valves b and c are closed,and valves e and f are open so that when the vapor pressure inside thebottle 20 is higher than the pressure of the carrier gas passing throughthe gas line, the precursor flows from the bottle 20 and enters into thestream of the carrier gas. When feeding only the carrier gas to thereaction chamber, as shown in (b) in FIG. 3, the carrier gas flowsthrough a gas line and passes through valve a while bypassing the bottle20. In the above, valves b, c, e, and f are closed.

FIG. 4 illustrates a precursor supply system using an APR with a BTOaccording to an embodiment of the present invention. As shown in (a) inFIG. 4, when a carrier gas flows through a gas line with a valve a to areaction chamber (not shown) without passing through a bottle 20, aprecursor gas enters into a stream of the carrier gas passing throughthe gas line where a gas line from the bottle 20 meets the gas linethrough which the carrier gas flows, and the carrier gas carries theprecursor therefrom and passes through an APR 30 and a valve g togetherwith the precursor, and is then fed to the reaction chamber togetherwith the precursor. In the above, valves b and c are closed, and valvese and f are open so that when the vapor pressure inside the bottle 20 ishigher than the pressure of the carrier gas passing through the gasline, the precursor flows from the bottle 20 and enters into the streamof the carrier gas. Valve g is an on-off valve, and when preventing theprecursor from entering into the reaction chamber, as shown in (b) inFIG. 4, valve g is closed so that neither the precursor nor the carriergas is fed to the reaction chamber.

In some embodiments, the process sequence may be set as illustrated inFIG. 7. FIG. 7 shows a schematic process sequence of PEALD in one cycleaccording to an embodiment of the present invention wherein a cell ingray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess. In this embodiment, a primary difference from the sequenceillustrated in FIG. 6 resides in “RF” which is conducted after purgingthe first precursor gas, followed by “Purge” before feeding the secondprecursor gas, so that adsorption of the first precursor can beimproved.

The sequence illustrated in FIG. 6 can be performed under the conditionsshown in Table 3 below.

TABLE 3 (numbers are approximate) Conditions for PEALD Cycle (Sequence#3) Substrate temperature 50 to 600° C. (preferably 100 to 400° C.)Pressure 50 to 4000 Pa (preferably 133 to 1000 Pa) 1^(st) precursorpulse 0.1 to 2 sec (preferably 0.3 to 1 sec) 1^(st) precursor purge 0.1to 10 sec (preferably 0.5 to 1 sec) RF power (13.56 MHz) 30 to 1000 W(preferably 50 to 200 W) for a 300-mm wafer RF power pulse 0.1 to 10 sec(preferably 0.2 to 5 sec) Purge 0.1 to 5 sec (preferably 0.1 to 1 sec)2^(nd) precursor pulse 0.1 to 2 sec (preferably 0.3 to 1 sec) 2^(nd)precursor purge 0.1 to 10 sec (preferably 0.5 to 1 sec) RF power (13.56MHz) 30 to 1000 W (preferably 50 to 200 W) for a 300-mm wafer RF powerpulse 0.1 to 10 sec (preferably 0.2 to 5 sec) Purge 0.1 to 5 sec(preferably 0.1 to 1 sec) Flow rate of reactant 10 to 2000 sccm(preferably 50 to 500 sccm) (continuous) for SiC; 10 to 2000 sccm(preferably 50 to 500 sccm) for SiCO; 10 to 2000 sccm (preferably 50 to500 sccm) for SiCN Carrier gas 1000 to 5000 sccm (preferably 2000 to4000 sccm) Dilution gas 0 to 5000 sccm (preferably 0 to 2000 sccm)Growth rate per cycle 0.01 to 0.1 nm/cycle (on a top surface)

In some embodiments, the process sequence may be set as illustrated inFIG. 8. FIG. 8 shows a schematic process sequence of thermal ALD in onecycle according to an embodiment of the present invention wherein a cellin gray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess. In this embodiment, one cycle of PEALD comprises “1^(st) Feed”where a first precursor gas (e.g., a Si-containing precursor gas) is fedto a reaction space via a carrier gas which carries the first precursorwithout feeding a second precursor to the reaction space, and also, adilution gas is fed to the reaction space, thereby adsorbing the firstprecursor gas onto a surface of a substrate via self-limitingadsorption; “Purge” where no first precursor nor second precursor is fedto the reaction space, while the carrier gas and the dilution gas arecontinuously fed to the reaction space, thereby removing non-adsorbedprecursor gas and excess gas from the surface of the substrate; “2^(nd)Feed” where a second precursor gas (e.g., a hydrocarbon-containingprecursor gas) is fed to the reaction space via a carrier gas whichcarries the second precursor without feeding the first precursor to thereaction space, and also, the dilution gas is continuously fed to thereaction space, thereby adsorbing the second precursor gas onto thefirst precursor-adsorbed surface of the substrate via self-limitingadsorption, wherein the ligand of the first precursor gas and the ligandof the second precursor gas undergo ligand substitution reaction; and“Purge” where the carrier gas and the dilution gas are continuously fedto the reaction space, without feeding the first and second precursorsto the reaction space, thereby removing by-products and excess gas fromthe surface of the substrate. Due to the continuous flow of the carriergas entering into the reaction space as a constant stream into which thefirst or second precursor is injected intermittently or in pulses,purging can be conducted efficiently to remove excess gas andby-products quickly from the surface of the layer, thereby efficientlycontinuing multiple ALD cycles.

In the sequence illustrated in FIG. 8, no reactant gas is used since thefirst and second precursors can undergo ligand substitution reactionwithout a reactant gas. The “adsorption” is more likely“polymerization”. This sequence is precursor-dependent becausereactivity of the precursors depends on the types of the ligandscontained in the first and second precursors. For example, when theligand is a hydroxyl group, after being adsorbed on the other precursor,some components are dissociated from the surface, and the componentsgenerate moisture which causes hydrolysis, thereby forming a bulk film.

The sequence illustrated in FIG. 8 can be performed under the conditionsshown in Table 4 below.

TABLE 4 (numbers are approximate) Conditions for Thermal ALD Cycle(Sequence #4) Substrate temperature 50 to 600° C. (preferably 100 to400° C.) Pressure 50 to 4000 Pa (preferably 133 to 1000 Pa) 1^(st)precursor pulse 0.1 to 2 sec (preferably 0.3 to 1 sec) 1^(st) precursorpurge 0.1 to 10 sec (preferably 0.5 to 1 sec) 2^(nd) precursor pulse 0.1to 2 sec (preferably 0.3 to 1 sec) 2^(nd) precursor purge 0.1 to 10 sec(preferably 0.5 to 1 sec) Carrier gas 1000 to 5000 sccm (preferably 2000to 4000 sccm) Dilution gas 1000 to 5000 sccm (preferably 500 to 2000sccm) Growth rate per cycle 0.01 to 0.1 nm/cycle (on a top surface)

In some embodiments, the process sequence may be set as illustrated inFIG. 9. FIG. 9 shows a schematic process sequence of thermal ALD in onecycle according to an embodiment of the present invention wherein a cellin gray represents an ON state whereas a cell in white represents an OFFstate, and the width of each column does not represent duration of eachprocess. In this embodiment, a primary difference from the sequenceillustrated in FIG. 8 resides in “Reactant” which is conducted afterpurging the second precursor gas, followed by “Thermal” wherein areactant gas is fed in “Reactant” and causes ligand substitutionreaction in “Thermal” wherein the ligand of the first precursor gas andthe ligand of the second precursor gas undergo ligand substitutionreaction to form a monolayer. “Reactant” is a period mainly forstabilizing the reactant flow, and “Thermal” is a period mainly forligand substitution reaction (in some embodiments, “Reactant” and“Thermal” are continuous integrated steps constituting a single step ofthermal ligand substitution reaction). After “Thermal”, “Purge” isconducted where the carrier gas and the dilution gas are continuouslyfed to the reaction space, without feeding the first and secondprecursors and the reactant gas to the reaction space, thereby removingby-products and excess gas from the surface of the substrate. Thissequence can improve adsorption of the first and second precursors andpromote ligand substitution reaction.

The sequence illustrated in FIG. 9 can be performed under the conditionsshown in Table 5 below.

TABLE 5 (numbers are approximate) Conditions for Thermal ALD Cycle(Sequence #5) Substrate temperature 50 to 600° C. (preferably 100 to400° C.) Pressure 50 to 4000 Pa (preferably 133 to 1000 Pa) 1^(st)precursor pulse 0.1 to 2 sec (preferably 0.3 to 1 sec) 1^(st) precursorpurge 0.1 to 10 sec (preferably 0.5 to 1 sec) 2^(nd) precursor pulse 0.1to 2 sec (preferably 0.3 to 1 sec) 2^(nd) precursor purge 0.1 to 10 sec(preferably 0.5 to 1 sec) Flow rate of reactant 10 to 2000 sccm(preferably 50 to 500 sccm) for SiC; 10 to 2000 sccm (preferably 50 to500 sccm) for SiCO; 10 to 2000 sccm (preferably 50 to 500 sccm) for SiCNReactant introduction 0.2 to 10 sec (preferably 1 to 5 sec) ThermalReaction duration 0.5to 60 sec (preferably 1 to 30 sec) Post reactionpurge 0.1 to 2 sec (preferably 0.1 to 1 sec) Carrier gas 1000 to 5000sccm (preferably 2000 to 4000 sccm) Dilution gas 0 to 5000 sccm(preferably 0 to 2000 sccm) Growth rate per cycle 0.01 to 0.1 nm/cycle(on a top surface)

In some embodiments, the process sequence may be set as illustrated inFIG. 10. FIG. 10 shows a schematic process sequence of PEALD in onecycle, followed by the schematic process sequence of PEALD illustratedin FIG. 6 or 7 according to an embodiment of the present inventionwherein a cell in gray represents an ON state whereas a cell in whiterepresents an OFF state, and the width of each column does not representduration of each process. In this embodiment, a SiC or SiCO film isformed according to the sequence illustrated in FIG. 6 or 7, andthereafter, a SiN film is formed, thereby alternately forming a SiC/SiCOfilm and a SiN film so as to form a SiCN or SiCON film, increasing heatresistance and/or chemical resistance. By incorporating Si—N bonds intothe SiC/SiCO film, heat resistance/chemical resistance of the film canbe improved. In this sequence, after the “Purge” following “2^(nd) Feed”in FIG. 6 or 7, a SiN cycle starts, wherein one cycle of PEALD comprises“Transit” where flow of the reactant gas (1^(st) reactant) used in thesequence illustrated in FIG. 6 or 7 is stopped, while continuouslyfeeding the carrier gas and the dilution gas to the reaction space,thereby purging the reaction space; “3^(rd) Feed” where a thirdprecursor gas (e.g., a Si-containing precursor gas) for forming a SiNfilm is fed to the reaction space via a carrier gas which carries thefirst precursor without feeding the first and second precursors and the1^(st) reactant gas and without applying RF power to the reaction space,and also, the dilution gas is continuously fed, and a 2^(nd) reactantgas is fed to the reaction space for forming a SiN film, therebychemisorbing the third precursor gas onto the surface of the substratevia self-limiting adsorption; “Purge” where none of the first, second,and third precursors and the 1^(st) reactant gas is fed to the reactionspace, while the carrier gas, the dilution gas, and 2^(nd) reactant gasare continuously fed to the reaction space, without applying RF power,thereby removing non-chemisorbed precursor gas and excess gas from thesurface of the substrate; “RF” where RF power is applied to the reactionspace while the carrier gas, the dilution gas, and 2^(nd) reactant gasare continuously fed to the reaction space, without feeding the first,second, and third precursors and the 1^(st) reactant gas, therebyforming a SiN monolayer through plasma surface reaction with the 2^(nd)reactant gas in an excited state; and “Purge” where the carrier gas, thedilution gas, and 2^(nd) reactant gas are continuously fed to thereaction space, without feeding the first, second, and third precursorsand the 1^(st) reactant gas and without applying RF power to thereaction space, thereby removing by-products and excess gas from thesurface of the substrate.

In this sequence, in some embodiments, the cycle for forming a SiC/SiCOfilm illustrated in FIG. 6 or 7 can be repeated m times, the cycle forforming a SiN film illustrated in FIG. 10 can be repeated n times, andthe cycle combining the cycle for a SiC/SiCO film and the cycle for aSiN film can be repeated p times, wherein m is an integer of 10 to 5000,preferably 50 to 2000, n is an integer of 10 to 5000, preferably 50 to2000, and p is an integer of 10 to 5000, preferably 50 to 2000.

The sequence illustrated in FIG. 10 can be performed under theconditions shown in Table 6 below.

TABLE 6 (numbers are approximate) Conditions for PEALD Cycle (Sequence#6) Substrate temperature Same as Sequence #2 or #3 Pressure Same asSequence #2 or #3 3^(rd) precursor pulse 0.1 to 5 sec (preferably 0.1 to1 sec) 3^(rd) precursor purge 0.1 to 5 sec (preferably 1 to 5 sec) Flowrate of 2^(nd) reactant 100 to 10000 sccm (preferably 1000 to(continuous) 5000 sccm) Carrier gas Same as Sequence #2 or #3 Dilutiongas Same as Sequence #2 or #3 RF power (13.56 MHz) 50 to 1000 W(preferably 100 to 500 W) for a 300-mm wafer RF power pulse 0.2 to 10sec (preferably 0.5 to 5 sec) Purge 0.1 to 2 sec (preferably 0.1 to 0.5sec) Growth rate per cycle 0.01 to 0.08 nm/cycle (on a top surface)

In the above sequence, the third precursor includes, but is not limitedto, a halogen-containing silane such as dichlorotetramethyldisilane,diiodosilane, etc. In some embodiments, the third precursor may beselected from the first precursors. The second reactant gas includes,but is not limited to, N₂, N₂/H₂, NH₃, NxHy (x>2; y>3), NxCyHz (x, y, zare integers), etc.

In some embodiments, a dual-chamber reactor (two sections orcompartments for processing wafers disposed close to each other) can beused, wherein a reactant gas and a noble gas can be supplied through ashared line whereas a precursor gas is supplied through unshared lines.

A skilled artisan will appreciate that the apparatus includes one ormore controller(s) (not shown) programmed or otherwise configured tocause the deposition and reactor cleaning processes described elsewhereherein to be conducted. The controller(s) are communicated with thevarious power sources, heating systems, pumps, robotics, and gas flowcontrollers or valves of the reactor, as will be appreciated by theskilled artisan.

The present invention is further explained with reference to workingexamples below. However, the examples are not intended to limit thepresent invention. In the examples where conditions and/or structuresare not specified, the skilled artisan in the art can readily providesuch conditions and/or structures, in view of the present disclosure, asa matter of routine experimentation. Also, the numbers applied in thespecific examples can be modified by a range of at least ±50% in someembodiments, and the numbers are approximate.

EXAMPLES

A SiC or SiCO film was formed on a Si substrate (Φ300 mm) havingtrenches with an aspect ratio (AR) of 2 or 3.5 (a width of 35 nm) bythermal ALD using a sequence illustrated in FIG. 8 (SQ #4) or FIG. 9 (SQ#5), and also by PEALD using a sequence illustrated in FIG. 5 (SQ #1),FIG. 6 (SQ #2), or FIG. 7 (SQ #3), one cycle of which was conductedunder the common conditions for all the sequences shown in Table 7, thecommon conditions for the sequences illustrated in FIGS. 5-9 shown inTables 8-12 below, respectively. For PEALD, the PEALD apparatusillustrated in FIG. 1A and a gas supply system (FPS) illustrated in FIG.2 were used. The specific conditions for each example are indicated inTable 13.

TABLE 7 (numbers are approximate) Common Conditions for Deposition CycleSubstrate temperature 400° C. Pressure 400 Pa Carrier gas Ar Flow rateof carrier gas (continuous) 2000 sccm

TABLE 8 (numbers are approximate) Conditions for PEALD Cycle (Sequence#1 (FIG. 5)) Precursor pulse 0.1 Sec Precursor purge 1 Sec RF power(13.56 MHz) for a 100 W 300-mm wafer RF power pulse 1 sec Purge 0.1 secDilution gas Ar: 100 Sccm

TABLE 9 (numbers are approximate) Conditions for PEALD Cycle (Sequence#2 (FIG. 6)) Si-precursor pulse 0.5 sec Si-precursor purge 0.5 secC-precursor pulse 1 sec C-precursor purge 1 sec Flow rate of reactantH2; 100 sccm for SiC; (continuous) O2; 100 sccm for SiCO Dilution gasAr: 100 sccm RF power (13.56 MHz) for a 100 W 300-mm wafer RF powerpulse 1 sec Purge 0.1 sec

TABLE 10 (numbers are approximate) Conditions for PEALD Cycle (Sequence#3 (FIG. 7)) Si-precursor pulse 0.5 sec Si-precursor purge 0.5 sec RFpower (13.56 MHz) for a 100 W 300-mm wafer RF power pulse 1 sec Purge0.1 sec C-precursor pulse 1 sec C-precursor purge 1 sec RF power (13.56MHz) for a 100 W 300-mm wafer RF power pulse 1 sec Purge 0.1 sec Flowrate of reactant H2; 100 sccm for SiC (continuous) Dilution gas Ar: 100sccm

TABLE 11 (numbers are approximate) Conditions for Thermal ALD Cycle(Sequence #4 (FIG. 8)) Si-precursor pulse 0.5 Sec Si-precursor purge 0.5Sec C-precursor pulse 1 Sec C-precursor purge 1 Sec Dilution gas Ar: 500sccm

TABLE 12 (numbers are approximate) Conditions for Thermal ALD Cycle(Sequence #5 (FIG. 9)) Si-precursor pulse 0.5 Sec Si-precursor purge 0.5Sec C-precursor pulse 1 sec C-precursor purge 1 sec Flow rate ofreactant 100 sccm Reactant pulse 1 sec Thermal Reaction pulse 5 sec Postreaction purge 1 sec Dilution gas Ar: 100 sccm

TABLE 13 (numbers are approximate) Reactant RF 1^(st) Precursor 2^(nd)Precursor (flow rate) [W] SQ Film *1 Divinyldimethylsilane — O₂ 100 1SiCO (0.1 slm) *2 Silacyclobutane — H₂ 100 1 SiC (0.1 slm)  3Bisdiethylaminosilane Ethyleneglycol O₂ 100 2 SiCO (0.1 slm)  4Bisdiethylaminosilane Ethyleneglycol — 4 SiCO  5 DiiodosilaneIodomethane H₂ 100 2 SiC (0.1 slm)  6 Diiodosilane Iodomethane — — 4 SiC 7 Diiodosilane Diiodomethane H₂ 100 2 SiC (0.1 slm)  8 DiiodosilaneDiiodomethane H₂ 100 3 SiC (0.1 slm)  9 Diiodosilane Diiodomethane H₂ —5 SiC (0.1 slm)

In Table 13, the Example numbers with “*” indicate comparative examples.Each obtained film was evaluated, and “Film” represents compositions ofthe film, and “SQ” represents the sequence number where SQ #1 to SQ #5correspond to the sequences illustrated in FIGS. 5 to 9, respectively.Table 10 shows the results of evaluation.

TABLE 14 (the numbers are approximate) AR 2 AR 3.5 Bottom BottomSidewall coverage Sidewall coverage GPC coverage (bottom/ coverage(bottom/ (nm/ RI@ (side/top) top) (side/top) top) cycle) 633 nm (%) (%)(%) (%) *1 0.03 1.6 90 92 70 90 *2 0.03 1.64 90 95 75 90  3 0.04 1.69 9593 92 95  4 0.02 1.67 96 95 9 95  5 0.04 1.7 93 95 93 93  6 0.02 1.65 9793 92 92  7 0.06 1.68 97 94 93 96  8 0.06 1.69 94 92 91 96  9 0.03 1.794 96 97 92

In Table 14, “GPC” represents growth rate per cycle, “Sidewall Coverage”represents a percentage of thickness of film deposited on a sidewallrelative to thickness of film deposited on a blanket surface (a topsurface of the substrate) at a trench having a specified aspect ratio (2or 3.5), “Bottom Coverage” represents a percentage of thickness of filmdeposited on a bottom surface relative to thickness of film deposited ona blanket surface at a trench having a specified aspect ratio (2 or3.5), and “RI@633 nm,” represents refractive index at a wavelength of633 nm.

In the above examples, a SiC film was formed using diiodosilane as afirst precursor and iodomethane or diiodomethane as a second precursorin thermal ALD (Example 6) and PEALD (Examples 5 and 7 to 9), and a SiCOfilm was formed using bisdiethyaminosilane as a first precursor andethyleneglycol as a second precursor in thermal ALD (Example 4) andPEALD (Example 3). As comparative examples, a SiC film was formed usingdivinyldimethylsilane as a single precursor in PEALD (Example 2), and aSiCO film was formed using divinyldimethylsilane as a single precursorin PEALD (Example 1). As a result, in all the examples, effectivereaction took place for both SiC film and SiCO film in thermal ALD at atemperature of 400° C., and also in PEALD. However, when the singleprecursor was used in Examples 1 and 2, overall step coverage wasinferior to that when the two precursors were used in Examples 3 to 9,and especially when the aspect ratio was 3.5, the sidewall coverage waspoor when the single precursor was used in Examples 1 and 2, as comparedwith that when the two precursors were used in Examples 3 to 9 whichshowed remarkable improvements on the step coverage. It was confirmedthat a carbon-containing film can successfully be formed with goodconformality (e.g., more than 90%) even on sidewalls of a trench havingan aspect ratio of more than 2 by using 1^(st) and 2^(nd) precursors incombination, wherein the 1^(st) precursor contains silicon and at leastone 1^(st) ligand, and the 2^(nd) precursor contains no silicon and atleast one 2^(nd) ligand, where the 1^(st) ligand and the 2^(nd) ligandcan undergo ligand substitution reaction.

The above remarkable results can be obtained when the 1^(st) precursorcontains a metal instead of silicon (or in combination), since ligandsubstitution reaction can similarly take place. In addition, the feedingorder of the 1^(st) precursor and 2^(nd) precursor can be reversed.

It will be understood by those of skill in the art that numerous andvarious modifications can be made without departing from the spirit ofthe present invention. Therefore, it should be clearly understood thatthe forms of the present invention are illustrative only and are notintended to limit the scope of the present invention.

We/I claim:
 1. A method for forming an oxide or nitride film containingcarbon and at least one of silicon and metal in a trench on a substrateplaced in a reaction space by atomic layer deposition (ALD) conductingone or more process cycles, each process cycle comprising: (i) feeding afirst precursor in a pulse to the reaction space to adsorb the firstprecursor on the substrate, said first precursor containing at least oneof silicon and metal, and a first functional group selected from thegroup consisting of a halogen group, —NR₂, and —OR, wherein each Rindependently represents hydrogen or hydrocarbon group; (ii) feeding asecond precursor in a pulse to the reaction space to adsorb the secondprecursor on the substrate, said second precursor containing neithersilicon nor metal, and a second functional group selected from the groupconsisting of a halogen group, —NR₂, and —OR, wherein each Rindependently represents hydrogen or hydrocarbon group, wherein thefirst and second functional groups are a combination of a halogen groupand —NR₂, a halogen group and —OR, a halogen group and halogen group, or—NR₂ and —OR; and (iii) forming a monolayer constituting an oxide ornitride film containing carbon and at least one of silicon and metal onthe substrate by undergoing a substitution reaction between the firstand second functional groups of the first and second precursors adsorbedon the substrate.
 2. The method according to claim 1, wherein the firstprecursor contains silicon.
 3. The method according to claim 2, whereinthe first precursor is one or more compounds selected from the groupconsisting of:

wherein each X is independently H, C_(x)H_(y), NH₂, NH(C_(x)H_(y)),N(C_(x)H_(y))₂, O(C_(x)H_(y)), or OH, each Y is independently F, Cl, Br,I, NH₂, NH(C_(x)H_(y)), or N(C_(x)H_(y))₂, and each Z is independentlyC_(x)H_(y) or N_(x)H_(y), wherein x and y are integers.
 4. The methodaccording to claim 1, wherein the second precursor is one or morecompounds selected from the group consisting of:

wherein each X is independently C_(x)O_(y), O(C_(x)H_(y)), NH₂,NH(C_(x)H_(y)), N(C_(x)H_(y))₂, or OH, each Y is independentlyC_(x)H_(y) or N_(x)H_(y), each A is independently H or C_(x)H_(y), andeach B is OH, C_(x)H_(y), O(C_(x)H_(y)), NH₂, NH(C_(x)H_(y)),N(C_(x)H_(y))₂, F, Cl, Br, or I, wherein x and y are integers.
 5. Themethod according to claim 1, wherein the first and second functionalgroups are an alkylamino group and a hydroxyl group, respectively, or ahalogen group and a halogen group, respectively.
 6. The method accordingto claim 1, wherein a noble gas is continuously fed to the reactionspace throughout the process cycle.
 7. The method according to claim 1,wherein the precursor is fed in a pulse to the reaction space using aflow-pass system (FPS), auto-pressure regulator (APR), or a bottle-outcontrol system (BTO).
 8. The method according to claim 2, wherein theoxide or nitride film is a film constituted by SiC, SiCO, SiCN, orSiCON.
 9. The method according to claim 1, wherein the ALD is thermalALD, and the substitution reaction is thermally performed.
 10. Themethod according to claim 1, wherein the ALD is plasma-enhanced ALD, andthe substitution reaction is performed using a plasma.
 11. The methodaccording to claim 9, wherein a reactant gas is fed continuously to thereaction space throughout each process cycle.
 12. The method accordingto claim 10, wherein the reactant gas is one or more gases selected fromthe group consisting of O₂, H₂, NH₃, and N₂.
 13. The method according toclaim 1, wherein each process cycle further comprises a purging stepbetween steps (i) and (ii), and between steps (ii) and (i) when theprocess cycle is repeated.
 14. The method according to claim 1, whereina sidewall coverage and a bottom coverage are 90% or higher, wherein thesidewall coverage is defined as a ratio of thickness of film on asidewall of the trench to thickness of film on a blanket surface at thetrench, and the bottom coverage is defined as a ratio of thickness offilm on a bottom of the trench to thickness of film on the blanketsurface at the trench.
 15. The method according to claim 11, wherein instep (iii), the monolayer is constituted by SiC or SiCO, and eachprocess cycle further comprises, after step (iii): (iv) switching thereactant gas to another reactant gas and feeding the another reactantgas continuously to the reaction space, (v) feeding a third precursor ina pulse to the reaction space to adsorb the third precursor on thesubstrate, said third precursor containing at least one of silicon andmetal and being reactive with excited species of the another reactantgas; and (vi) applying RF power to the reaction space to excite theanother reactant gas to react with the third precursor adsorbed on themonolayer or monolayers obtained in step (iii) to form thereon amonolayer or monolayers constituting a nitride film containing at leastone of silicon and metal.